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Activation of a cryptic streptomycin‐resistance gene in the Bacteroides erm transposon, Tn4551
Author(s) -
Smith C. Jeffrey,
Owen Charles,
Kirby Lyndon
Publication year - 1992
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1992.tb01404.x
Subject(s) - biology , transposable element , genetics , gene , homology (biology) , bacteroides , locus (genetics) , streptomycin , nucleic acid sequence , sequence analysis , plasmid , microbiology and biotechnology , mutant , bacteria , antibiotics
Summary Bacteroides compound transposons encoding erm resistance are highly homologous but previous studies have shown some divergence of Tn4551. Results presented here describe a novel Tn 4551 streptomycin‐resistance gene, aadS , that was phenotypically silent in wild‐type Bacteroides. However, aadS expression could be activated by a trans‐acting chromosomal mutation. The aadS ‐encoded peptide displayed significant homology to Gram‐positive streptomycin‐dependent adenyltransferases, and enzymatic analysis confirmed the production of this activity. Examination of the nucleotide sequence showed that 200 bp upstream of aadS , the DNA base composition changed abruptly from 31% G+C to 48% G+C. These two regions were demarcated by a DNA sequence with homology to the recombination hot spots reported for Tn21 and the Bacteroides ermFU gene and to sequences at the ends of the chromosomal Bacteroides conjugal element, XBU4422.